pub fn dp_rec_mc(amount: u32) -> u32 {
    let nums = vec![100, 50, 30, 20, 10, 5, 2, 1];
    let mut cnt = 0;
    let mut n = amount;
    for i in 0..nums.len() {
        if n < nums[i] {
            continue;
        }
        let tmp = n / nums[i];
        cnt += tmp;
        n -= tmp * nums[i];
    }
    cnt
}
